This open-label, single center study will assess the pharmacokinetics, efficacy and safety of mycophenolate mofetil in lung allograft recipients. Participants will be split into 2 groups according to the original disease: Group A (cystic fibrosis) and Group B (chronic obstructive pulmonary disease [COPD], emphysema, idiopathic pulmonary fibrosis, alpha-1 antitrypsin deficiency [A1AD]). All participants will receive mycophenolate mofetil orally, 1.5 grams (g) twice daily (BID) from Day 2 to 30 post transplantation, and 1 g BID from Day 31 to 90 post transplantation. Anticipated time on study treatment is 90 days, and target sample size is 50-100 individuals.